1. Field of the Invention
The present invention relates to an auger type ice making machine using a motor-driven auger, and more specifically, to an auger for an auger type ice making machine capable of reducing drive torque and the like.
2. Description of the Related Art
As is known well, an auger type ice making machine supplies ice-making water into a refrigerated casing having a cooling pipe wound around the outer periphery thereof, scratches or scrapes an ice layer iced around the inner periphery of the refrigerated casing by an auger having a spiral blade, and forces the scratched ice into an ice compressing passage of a press head positioned at the upper end portion of the refrigerated casing so as to continuously make, for example, ice cubes.
FIG. 7 is an enlarged view partly showing a spiral blade of a conventional auger type ice making machine, wherein numeral 1 denotes a refrigerated casing, numeral 2 denotes an auger rotatably disposed in the refrigerated casing 1, numeral 3 denotes a spiral blade formed around the outer periphery of the auger 2, and numeral 4 denotes a cooling pipe wound around the outer periphery of the refrigerated casing 1. As is apparent from a longitudinal cross sectional view shown in FIG. 7, the outermost portion in a radial direction of the conventional spiral blade 3 is composed of a lower side axial or vertical portion 3a and an upper side tapered portion 3b which inclines upwardly and inwardly in the radial direction from the vertical portion 3a, so that when the spiral blade 3 is advanced in a screw fashion by rotating the auger 2, the spiral blade 3 wears away or scratches or scrapes an ice layer 5 at the boundary between the vertical portion 3a and the tapered portion 3b.
Further, as shown in FIG. 8, there is also known a spiral blade 7 of an auger 6 which has the outermost portion in the radial direction thereof composed only of a tapered portion 7c extending upward while inclining outwardly, so that the ice layer 5 is worn away or scratched or scraped by the upper edge at the extreme end of the tapered portion 7c.
Consideration will be made to a given portion of the refrigerated casing 1 in relation to the auger including the spiral blade 3 shown in FIG. 7. When a portion of the spiral blade 3 scratches an ice layer at the given portion and then the portion of the spiral blade 3 returns to the given portion again, ice grows on the ice layer which could not be scratched by the spiral blade 3. Since the grown ice strongly presses the vertical portion 3a in the radial direction and applies an excessive load to the auger 2, a problem arises in that the refrigerated casing 1 is deformed and the burden of the bearing (not shown) of the auger 2 is increased unless a scratching force is increased by increasing a drive force of a motor for driving the auger 2. Further, a problem also arises in that ice is held between the inner periphery of the refrigerated casing 1 and the vertical portion 3a in a compressed state and noise may be made when the ice is scratched.
On the other hand, the auger provided with the spiral blade 7 shown in FIG. 8 can prevent the application of an excessive load to the auger 6 because blade 7 does not include a vertical portion. However, since the surface of the taper portion 7c faces downward and does not act to feed ice upward under pressure, when a clearance between the blade tip and the refrigerated casing is increased because the outside dimension of the blade tip is made relatively small by a production error or reduced by wear or the like, there is caused a drawback that ice making capability is extremely lowered.